Measuring cfDNA integrity as a biomarker for predicting neoadjuvant chemotherapy response in breast cancer patients: a pilot study

PURPOSE

Circulating cell-free DNA (cfDNA) is a promising biomarker for predicting treatment response and disease outcomes in Breast Cancer (BC) patients undergoing neoadjuvant chemotherapy (NAC). To determine if cfDNA originates from tumors, matching tumor and cfDNA gene mutations are necessary, often requiring tumor DNA sequencing. We assessed plasma cfDNA integrity by measuring concentrations and ratios of larger-to-smaller Alu DNA fractions as a potential biomarker, eliminating the need for prior tumor sequencing.

METHODS

We included patients with localized and/or locally advanced BC receiving standard NAC alone or in combination with immunotherapy and/or anti-HER2 targeted therapy. Blood samples were collected before treatment, every 2 weeks during treatment, and before surgery.

RESULTS

Of the 38 evaluated patients, only 28 completed the protocol and underwent surgery after NAC. Seven patients (25%) achieved a pathologic complete response (pCR). We found that cfDNA integrity (cfDNAI) levels at 15 days after starting NAC were significantly higher in patients who achieved pCR (p = 0.045) and correlated significantly with Disease-Free Survival (DFS) in univariate analysis (p = 0.0371).

CONCLUSIONS

Evaluation of cfDNAI 2 weeks after NAC initiation appears to be an early biomarker for tumor pCR and DFS. Measuring Alu fragments of different lengths may replace techniques requiring prior tumor sequencing to measure ctDNA, reducing costs and complexity of cfDNA serial measurements in BC patients undergoing NAC.

Locus-Specific Bisulfate NGS Sequencing of GSTP1, RNF219, and KIAA1539 Genes in the Total Pool of Cell-Free and Cell-Surface-Bound DNA in Prostate Cancer: A Novel Approach for Prostate Cancer Diagnostics

The locus-specific methylation of three genes (GSTP1, RNF219, and KIAA1539, also known as FAM214B) in the total pool of blood cell-free DNA, including cell-free DNA from plasma and cell-surface-bound DNA, of patients with prostate cancer and healthy donors was studied on the MiSeq platform. Our study found a higher methylation index of loci for total cell-free DNA compared with cell-free DNA. For total cell-free DNA, the methylation of GSTP1 in each of the 11 positions provided a complete separation of cancer patients from healthy donors, whereas for cell-free DNA, there were no positions in the three genes allowing for such separation. Among the prostate cancer patients, the minimum proportion of GSTP1 genes methylated in any of the 17 positions was 12.1% of the total circulated DNA fragments, and the minimum proportion of GSTP1 genes methylated in any of the 11 diagnostically specific positions was 8.4%. Total cell-free DNA was shown to be more convenient and informative as a source of methylated DNA molecules circulating in the blood than cell-free DNA.

Role of Cell-Free DNA and Deoxyribonucleases in Tumor Progression

Many studies have reported an increase in the level of circulating cell-free DNA (cfDNA) in the blood of patients with cancer. cfDNA mainly comes from tumor cells and, therefore, carries features of its genomic profile. Moreover, tumor-derived cfDNA can act like oncoviruses, entering the cells of vulnerable organs, transforming them and forming metastatic nodes. Another source of cfDNA is immune cells, including neutrophils that generate neutrophil extracellular traps (NETs). Despite the potential eliminative effect of NETs on tumors, in some cases, their excessive generation provokes tumor growth as well as invasion. Considering both possible pathological contributions of cfDNA, as an agent of oncotransformation and the main component of NETs, the study of deoxyribonucleases (DNases) as anticancer and antimetastatic agents is important and promising. This review considers the pathological role of cfDNA in cancer development and the role of DNases as agents to prevent and/or prohibit tumor progression and the development of metastases.